[master] 81381076f gc unused SLTs (VSL tags)

[Nils Goroll]

commit 81381076fa9d5bdae543e3fd788fea0586f2fbf1
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon Mar 6 15:33:57 2023 +0100

    gc unused SLTs (VSL tags)
    
    Now that we broke the VSL format, this is the time to act.

diff --git a/doc/changes.rst b/doc/changes.rst
index 7d63ec4b1..fbda69fe8 100644
--- a/doc/changes.rst
+++ b/doc/changes.rst
@@ -72,6 +72,12 @@ Varnish Cache NEXT (2023-03-15)
 
     ``debug.xid 20000000000``
 
+* Consequently, VSL clients (log processing tools) are now
+  incompatible with logs and in-memory data written by previous
+  versions, and vice versa.
+
+* Unused log tags (SLTs) have been removed.
+
 * The ``debug.xid`` CLI command now sets the next XID to be used,
   rather than "one less than the next XID to be used"
 
diff --git a/doc/sphinx/whats-new/changes-trunk.rst b/doc/sphinx/whats-new/changes-trunk.rst
index 4df5b8236..8333e2bde 100644
--- a/doc/sphinx/whats-new/changes-trunk.rst
+++ b/doc/sphinx/whats-new/changes-trunk.rst
@@ -111,7 +111,7 @@ varnishlog
 The in-memory and on-disk format of VSL records changed to allow 64bit VXID
 numbers. The new binary format is not compatible with previous versions, and
 log dumps performed with a previous Varnish release are no longer readable
-from now on.
+from now on. Consequently, unused log tags have been removed.
 
 The VXID range is limited to ``VRT_INTEGER`` to fit in VCL the variables
 ``req.xid``, ``bereq.xid`` and ``sess.xid``.
diff --git a/include/tbl/vsl_tags.h b/include/tbl/vsl_tags.h
index 9e28d92e0..20a563dae 100644
--- a/include/tbl/vsl_tags.h
+++ b/include/tbl/vsl_tags.h
@@ -119,18 +119,6 @@ SLTM(BackendOpen, 0, "Backend connection opened",
 	"\n"
 )
 
-SLTM(BackendReuse, 0, "Backend connection put up for reuse",
-	"Logged when a backend connection is put up for reuse by a later"
-	" connection.\n\n"
-	"The format is::\n\n"
-	"\t%d %s\n"
-	"\t|  |\n"
-	"\t|  +- Backend display name\n"
-	"\t+---- Connection file descriptor\n"
-	"\n"
-	NOSUP_NOTICE
-)
-
 SLTM(BackendClose, 0, "Backend connection closed",
 	"Logged when a backend connection is closed.\n\n"
 	"The format is::\n\n"
@@ -166,19 +154,6 @@ SLTM(ProxyGarbage, 0, "Unparseable PROXY request",
 	"A PROXY protocol header was unparseable.\n\n"
 )
 
-SLTM(Backend, 0, "Backend selected",
-	"Logged when a connection is selected for handling a backend"
-	" request.\n\n"
-	"The format is::\n\n"
-	"\t%d %s %s\n"
-	"\t|  |  |\n"
-	"\t|  |  +- Backend display name\n"
-	"\t|  +---- VCL name\n"
-	"\t+------- Connection file descriptor\n"
-	"\n"
-	NOSUP_NOTICE
-)
-
 SLTM(Length, 0, "Size of object body",
 	"Logs the size of a fetch object body.\n\n"
 )
@@ -623,18 +598,6 @@ SLTM(Witness, 0, "Lock order witness records",
 	"Diagnostic recording of locking order.\n"
 )
 
-SLTM(BackendStart, 0, "Backend request start",
-	"Start of backend processing. Logs the backend IP address and port"
-	" number.\n\n"
-	"The format is::\n\n"
-	"\t%s %s\n"
-	"\t|  |\n"
-	"\t|  +- Backend Port number\n"
-	"\t+---- Backend IP4/6 address\n"
-	"\n"
-	NOSUP_NOTICE
-)
-
 SLTM(H2RxHdr, SLT_F_BINARY, "Received HTTP2 frame header",
 	"Binary data"
 )